Freestyle what would happen if i put 2 spacers behind my impeller.

[txsuperjetfreak96]

ive got a 12/20 skat prop in my 96 rn, ive got an extra spacer laying around, what would happen if i put 2 spacers behind the prop, Im thinking it would hurt my bottom end since is moveing it further away from the pump but not sure, what kind of gains or non gains i would get from this.

 

[Patrick Star]

I don't think the wear ring would fit once you go to bolt the pump sections together with 2 spacers. You want the impeller closer to the stator to make the pump more effective. I just put in a hooker and it barely fit, but once I got the wear ring tapped down it was perfect.

 

[Mark44]

Most people have them cut back.

Mark44

 

[Pablo]

art gomez talked to me about this and it's pros and cons. I forget most of the specifics, but he had talked me into putting a little more space between my impeller for improved hook up. You'd really need to call him to get a real explanation, but it sounded logical and I was about to try it but forgot to make the changes. Prolly will on a new hull this fall though..

 

[sjetrider]

this is new. Mag pumps have less space between the viens and prop than OEM and they are much more efficient IMO. I cant imagine whay you would want the prop further from the viens??????????

 

[Idok]

adding spacers will make it slightly less agressive.......so, if you have a prop you think its just a little too tall, add a washer

 

[Matt_E]

this is new. Mag pumps have less space between the viens and prop than OEM and they are much more efficient IMO. I cant imagine whay you would want the prop further from the viens??????????

My mag pump Was set up by Jetworks and has at least one spacer. That was more about the guys at Skat cutting my new impeller too close, though.
The impeller being closer to the pump vanes loads the engine quicker. That can be a bad thing, depending on the engine

 

[sjetrider]

seems like a recipie for loosing hook up quicker and causing some handling issues as well. If your prop is too tall just pitch it down and keep the hook up and gain a little bottom end snap at the same time right or no?

 

[kevbo]

The "cut back prop" is just something people do here as a matter of course and swear that it makes a difference, just like the stubby cone. I could not change peak rpm or top speed by moving the prop in or out, although I never tried to place it all the way against the stator vanes. The stubby cone also made no measurable change in load or speed.

 

[snowxr]

The "cut back prop" is just something people do here as a matter of course and swear that it makes a difference, just like the stubby cone. I could not change peak rpm or top speed by moving the prop in or out, although I never tried to place it all the way against the stator vanes. The stubby cone also made no measurable change in load or speed.

The cutback prop and stubby cone are intended to improve low end hookup. At top speed neither would make much of a differance.

 

[waxhead]

Cutting back will allow you to reload the pump faster. it also loads the engine more as there is less area for the water to change direction as it comes off the prop to the pump veins.
If you wish to put your prop forward to unload your engine I would suggest your better of repitching the prop to better suit your engine

 

[txsuperjetfreak96]

yeah i wasnt sure thought i saw somewhere on here about someone talking bout different, spacers, i may not b as sure as i thought i was, fixing to send a reduction nozzle to zero and get it tapered bored to 85mm

 

[Speedfreak]

The "cut back prop" is just something people do here as a matter of course and swear that it makes a difference, just like the stubby cone. I could not change peak rpm or top speed by moving the prop in or out, although I never tried to place it all the way against the stator vanes. The stubby cone also made no measurable change in load or speed.

I agree 100% on a close to stock ski. I done the washer then no washer then 5mm cut back with and without a stubby cone and felt no noticeable difference with a slightly limited ski. BUT after I got my 5mm 850 motor all dialed in boring the nozzle 2 mm was a noticeable difference. Changing the cone and cutback would have a dramatic effect as far as how and when the ski hit. It was noticeable especially with the motor/pipe setup as a light switch.

 

[Waternut]

The "cut back prop" is just something people do here as a matter of course and swear that it makes a difference, just like the stubby cone. I could not change peak rpm or top speed by moving the prop in or out, although I never tried to place it all the way against the stator vanes. The stubby cone also made no measurable change in load or speed.

I know you have lots of cool stuff to do testing and I'm not questioning your results but I am questioning your conclusion. You're testing mods designed to alter pump loading at peak rpms and top speed. In my mind, that's like testing a 20" diameter drag slick and a 20" diameter wheel off a geo metro and saying they make no difference in how fast the car goes. Theoretically the two tires will spin the same speed and therefore should move the car at the same speed but one will be more efficient at getting the car moving and one will produce less drag at top speed so the differences between the two will be related to the conditions in which they're used. The same holds true for the props. One produces less load on the engine and therefore will allow the engine to spin up faster which will increase acceleration provided the pump can stay hooked up. The other will load the engine more and it won't spin up as fast but will have a greater chance of stay connected to the water and this can increase acceleration.

Right?

 

[kevbo]

RPM stayed the same during acceleration too. This was with a worx grate, 85mm nozzle, and a 701 turning 6900 at 48 mph. My only conclusion is that the pitch and nozzle diameter are very important to performance. Stubby cones and prop location are much harder to measure and in this case impossible to detect any differences. All this was in clear water, most "hookup" enhancing mods like pump stuffers and large hub props have shown to have limited value in clear water. The Worx grate is wonderful though.

 

[Waternut]

RPM stayed the same during acceleration too. This was with a worx grate, 85mm nozzle, and a 701 turning 6900 at 48 mph. My only conclusion is that the pitch and nozzle diameter are very important to performance. Stubby cones and prop location are much harder to measure and in this case impossible to detect any differences. All this was in clear water, most "hookup" enhancing mods like pump stuffers and large hub props have shown to have limited value in clear water. The Worx grate is wonderful though.

I'll buy that conclusion.